The proposed research will study by several techniques the interactions of cell surface proteins with the external environment (hormones, other cells) and with the cytoskeleton. The tools used for the proposed work include the use of monoclonal antibodies to identify developmentally regulated surface molecules and studies of the physical properties of cell surface molecules. The systems under investigation are growth control in 3T3 cells and Schwann cells, and developmental changes in the embryonal nervous system with particular emphasis on the neural retina.